Spaceteam is a great app that we haven't mentioned much, but the TUAW team certainly knows about it, as we played during most of our downtime at Macworld. The lastest update has made it even better.
Spaceteam is based on an amazing idea. It's a multiplayer game for one to four (or more, see below) iOS devices. Every player gets a panel of seemingly nonsensical touchscreen controls for a space ship, and gets orders for those controls ("push button 1" or "turn knob to 3," for example) at the top of the screen. The twist, however, is that the command you get is usually for controls on someone else's screen. When played correctly, the game prompts you and your friends to shout crazy commands to each other, like "Turn the astro-generator to five!" or "Jump-start the blast engine!"
With the new update, Spaceteam is absolutely free to download. There are new IAP packs to buy, which unlock new skins or control sets, or even open up new challenges or achievements to earn. Additionally, new massive multiplayer modes let you mess around with more than four players if you happen to have a larger group.
So not only is the game great, but the devs are working hard to provide lots of other content. It's quite impressive, even beyond the initial idea of just having players, as the description says, "shout technobabble at each other until their ship explodes." If you haven't tried Spaceteam yet, it's a must-play -- go grab a friend with another iOS device, and have some fun.